This paper reports findings from a study on slum improvement projects to show the difference that environmental assessment (EA) can make in such interventions and to suggest mechanisms for its integration into such projects. The findings are based on a field survey that was carried out in two slums of Dhaka where infrastructure projects were implemented. In one slum, the EA process was considered in designing and locating infrastructure and in the other it was not. The survey results traced the severe problems that existed in both slums before the implementation of infrastructure improvement projects and reveal that after the intervention the situation has considerably improved in the slum where EA was conducted. In contrast, some problems still persist in the other slum where EA was not considered. To make it worse, the newly built infrastructures have even given rise to a set of new problems. In order to avoid such negative outcomes from development interventions, the paper finally develops the mechanism for integration of EA into slum improvement project.